Failures to beacon.min.js

Since the beginning of this month (July 2020) we’ve seen a signficant uptick in the number of failures from the beacon for browser insights.This appears to mostly be IE 11. Has anyone else noticed this? I did see (via doing diffs in the wayback machine) some changes were applied to around June 23rd.

Uncaught SecurityError: Failed to execute ‘sendBeacon’ on ‘Navigator’: sendBeacon() with a Blob whose type is not any of the CORS-safelisted values for the Content-Type request header is disabled temporarily. See for details.

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Same here!


Received a response from support, I’m including the relevant bit here.

Cloudflare use beacons in order to get the client’s data back to us.
This issue is fixed in Chrome v81:
We have also added a change to fall back to use ajax instead if the browser does not support sending beacons.